<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            background-color: pink;
            margin: 10px;
            padding: 20px;
            border: 15px solid red;
        }
    </style>
    <script src="js/jQuery.min.js"></script>
</head>
<body>
    <div></div>
    <script>
        $(function(){
            console.log($('div').width());
            // $('div').width(300);
            console.log($('div').innerWidth());
            console.log($('div').outerWidth(true));
        })
    </script>
</body>
</html>